1. Field of the Invention
The present invention relates to a sliding shuttering or formwork machine for constructing continuously concrete roadways or pavements, of the type comprising a main frame having transversely spaced ground engaging members allowing it to move over the ground, two lateral transversely spaced shutterings or side forms extending longitudinally between the ground engaging members, a conforming plate, sometimes also referred to in the art as a "slipform pan" or as an "extrusion plate", and hereinafter called the "main extrusion plate", said main extrusion plate extending transversely between the lateral shutterings and forming therewith a tunnel shaped sliding shuttering or formwork for extruding a mass of concrete and molding same into a thick pavement as the machine moves forward, the main extrusion plate being mounted for vertical movement with respect to the main frame, adjustment means mounted between the main frame and the main extrusion plate for adjusting the vertical position thereof with respect to the ground and, consequently, the thickness of the concrete pavement to a desired value, and concrete supply and distribution means disposed in front of the main frame for delivering said concrete mass onto the ground in front of said main extrusion plate.
2. Description of the Prior Art
Sliding shuttering machines are well known (see patents U.S. Nos. 4,073,592, 4,312,602, 4,025,217, 3,177,784 and DE 2 108 846). Among them, machines of the "Guntert and Zimmermann" type are more especially known. They are described more particularly by M. Ray and Y. Charonnat in pages 92-103 of the "Bulletin de Liaison du Laboratoire des Ponts et Chaussees" No. 95, of May-June 1968, ref 2 231. With them, concrete road surfaces, reinforced or not, may be constructed at high rates reaching 200 m.sup.3 per hour with a minimum of human intervention. In the case where the concrete is not reinforced, it is poured directly in front of the machine from trucks. If the concrete is to be reinforced, the reinforcements are placed in front of the machine as it moves forward. In this latter case, the trucks no longer have direct access in front of the extrusion plate of the machine and a lateral feeding system must necessarily be used (see FIG. 9, page 104, in the above-mentioned Bulletin). Said feeding system comprises a receiving hopper offset laterally for receiving the concrete unloaded from the trucks, and supply and distribution endless belts or aprons for transporting the concrete from the receiving hopper and distributing it in front of the extrusion plate. As the machine moves forward, the longitudinal reinforcements must be positioned with regular spacing in the transversal direction over the whole width of the surface to be concreted and adjusted vertically by elements called "spacers" serving both as transverse reinforcements and as supports for the longitudinal reinforcements. Positioning of the spacers on the ground over the whole width of the surface to be concreted constitutes a difficult and delicate operation. In addition, the lateral feeding of the concrete and positioning of the reinforcements sets a problem when the width of the available space is limited (in case of motor ways), making movement of the concrete supply trucks difficult, to the extent of bringing into question the usual work rates.